Lecture 6 - Quasi-Experimental & Correlational Designs

Question 1

A written research report should provide:

a. a detailed explanation of statistical procedures used in the experiment.
b. the raw data obtained from the experiment.

c. the names of the participants who were in the
experiment.

d. enough information to allow others to
understand, evaluate, and replicate the experiment.

Answer 1

d

Question 2

A study explored whether gender or degree being studied affected amount of binge drinking. Which factor is a true independent variable?

a. Gender.
b. Degree.
c. Both.
d. Neither.

Answer 2

c

Question 3

In 1957 APA President Lee Cronbach described psychology as consisting of two disciplines.

What were they?

Answer 3

Experimental research
(manipulated variables)

Correlational research
(subject variables)

Question 4

Correlational research focuses on _____ variables that vary across individuals and situations.

Answer 4

Subject variables -

• Attributes that pre- exist the study or attributes that occur naturally during the study.
• Subject variables can be studied with a range of methods.

Question 5

What are quasi-experimental designs?

Answer 5

Like a true experiment, a quasi-experimental design aims to establish a cause-and-effect relationship between an independent and dependent variable.

However, unlike a true experiment, a quasi-experiment does not rely on random assignment. Instead, subjects are assigned to groups based on non-random criteria.

Quasi-experimental design is a useful tool in situations where true experiments cannot be used for ethical or practical reasons.

They contain an IV and a DV like a true experiment.

Question 6

What are some limitations to a quasi-experimental design?

Answer 6

1. The lack of random assignment in quasi- experimental designs means we need to be more cautious about causal inferences.
   • In true experimental designs, assuming no confounds, we can infer that IV causes DV.
   • In quasi-experimental designs, groups may differ in several ways, so IV cannot be said to cause DV.
2. Quasi-experiments require an extra task – critical thinking about confounds & other problems that might result from the lack of random assignment

Question 7

What are correlational designs?

Answer 7

Correlational designs involve two or more variables that you cannot manipulate experimentally.

A correlation is also a statistical technique used to determine the degree to which two variables are related.

Not all correlational research designs reports correlations in their statistical tests. So the test is not the identifier of the design.

Question 8

In a positive correlation:

a. high scores on one variable are accompanied by high scores on the second variable
b. low scores on one variable are accompanied by low scores on the second variable
c. high scores on one variable are accompanied by low scores on the second variable
d. both alternatives a. and b.

Answer 8

d

Question 9

What is regression?

Answer 9

Regression is a statistical process for predicting individual scores AND estimating the accuracy of those predictions.

Regression allows you to use a predictor variable (X) to predict a criterion variable (Y).

Regression line – straight line on a scatterplot that best summarises a correlation.

Question 10

Correlation & Causation

To accurately interpret the results of correlational research, we need to consider two problems.

What are they?

Answer 10

Direction of causation problem:
a correlation does not indicate which variable is the cause and which is the effect.

Third variable problem:
the correlation between two variables may be the result of some third, unspecified variable.

Question 11

In his 1957 “two disciplines” address, Cronbach expressed concern that:

a. correlational psychology held secondary status among researchers
b. psychologists were relying too heavily on correlational techniques
c. researchers were abandoning the laboratory for clinical practice
d. psychologists no longer thought of their discipline as scientific

Answer 11

a